Prickly heat, also known as heat rash or miliaria, is caused when the sweat ducts in the skin become clogged or narrowed, leading to sweat being trapped beneath the skin surface. This trapped sweat causes inflammation, irritation, and the characteristic rash with small bumps or blisters. The blockage prevents sweat from reaching the skin's surface and evaporating, which cools the body, thus causing the skin irritation. Common causes of sweat duct clogging and resulting prickly heat include:
- Hot and humid weather
- Excessive sweating due to physical activity or fever
- Wearing tight or warm clothing
- Prolonged skin contact with surfaces or clothing that block sweat evaporation
- Using certain bandages, medicine patches, or medications that increase sweating
- Conditions causing excessive sweating (hyperhidrosis)
- More common in babies and young children whose sweat ducts are still developing
Prickly heat frequently occurs in body areas where skin folds or touches skin, such as under the breasts, inner thighs, and underarms. In summary, prickly heat is caused by sweat glands becoming blocked, trapping sweat beneath the skin, which inflames and irritates the skin.
